Busbar assembly for current sensing

ABSTRACT

A busbar assembly includes a base having a width and a length. The base has a first surface and a second surface and has a first side and a second side. A distance between the first side and the second side comprises the width, and the base defines a slot centered between approximately 75% and approximately 79% of the width.

INTRODUCTION

The present disclosure relates to busbar assemblies, and moreparticularly to busbar assemblies for current sensing.

Vehicles, such as battery-electric vehicles (BEVs), plug-inhybrid-electric vehicles (PHEVs), mild hybrid-electric vehicles (MHEVs),or full hybrid-electric vehicles (FHEVs), may contain one or more energystorage devices, such as a high voltage (HV) battery, that functions asa propulsion source for the vehicle. The HV battery may includecomponents and systems to assist in managing vehicle performance andoperations. The HV battery may also include one or more arrays ofbattery cells interconnected electrically between battery cell terminalsand interconnector busbars

SUMMARY

According to several aspects of the present disclosure, a busbarassembly includes a base having a width and a length. The base has afirst surface and a second surface and has a first side and a secondside. A distance between the first side and the second side comprisesthe width, and the base defines a slot centered between approximately75% and approximately 79% of the width.

In other features, the base defines the slot centered betweenapproximately 76% and approximately 78% of the width.

In other features, the base defines the slot centered at 77% of thewidth.

In other features, the slot comprises an aperture extending through thebase.

In other features, the base further defines a channel between the firstside and the second side.

In other features, the busbar assembly includes a printed circuit boarddisposed over the first surface, wherein a flanged portion of theprinted circuit board extends through the channel, where the flangedportion includes at least one current sensing device configured tomeasure current parameters of current flow through the base.

In other features, the at least one current sensing device comprises apoint field detector.

In other features, the at least one current sensing device isgalvanically isolated from the base.

In other features, the width is at least four times the thickness.

According to several aspects of the present disclosure, busbar assemblyincludes a base having a width and a length, the base having a firstsurface and a second surface and having a first side and a second side.A distance between the first side and the second side comprises thewidth of the base, and the base defines a slot centered betweenapproximately 75% and approximately 79% of the width. The busbarassembly includes a printed circuit board disposed over the firstsurface. A flanged portion of the printed circuit board extends througha channel, and the flanged portion includes at least one current sensingdevice configured to measure current parameters of current flow throughthe base.

In other features, the base defines the slot centered betweenapproximately 76% and approximately 78% of the width.

In other features, the base defines the slot centered at 77% of thewidth.

In other features, the slot comprises an aperture extending through thebase.

In other features, the base further defines the channel between thefirst side and the second side.

In other features, the at least one current sensing device comprises apoint field detector.

In other features, the at least one current sensing device isgalvanically isolated from the base.

In other features, the width is at least four times a thickness of thebase.

According to several aspects of the present disclosure, busbar assemblyincludes a base having a width and a length, the base having a firstsurface and a second surface and having a first side and a second side.A distance between the first side and the second side comprises thewidth of the base. The base defines a slot centered betweenapproximately 75% and approximately 79% of the width and the width is atleast four times a thickness of the base. The busbar assembly includes aprinted circuit board disposed over the first surface. A flanged portionof the printed circuit board extends through a channel, and the flangedportion includes at least one current sensing device configured tomeasure current parameters of current flow through the base.

In other features, the base defines the slot centered betweenapproximately 76% and approximately 78% of the width.

In other features, the base defines the slot centered at 77% of thewidth.

Further areas of applicability will become apparent from the descriptionprovided herein. It should be understood that the description andspecific examples are intended for purposes of illustration only and arenot intended to limit the scope of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

FIG. 1 is a schematic diagram of an example battery electric vehicleaccording to an example implementation;

FIG. 2A is an isometric view of a busbar assembly according to anexample implementation;

FIG. 2B is an isometric view of a busbar assembly according to anexample implementation;

FIG. 3 is an isometric view of a busbar assembly including a printedcircuit board disposed over a surface of the busbar assembly accordingto an example implementation; and

FIG. 4 is a side view of a busbar assembly including a printed circuitboard disposed over a surface of the busbar assembly according to anexample implementation.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses.

In some vehicle environments, busbars are used within vehicle batteryassemblies, e.g., battery packs, to provide for local current powerdistribution. In some implementations, busbars may incorporate currentsensing capabilities for control and protection of electroniccomponents. However, current busbars may fail to provide suitablecurrent sensing capabilities due to external disturbances, lack ofgalvanic isolation, and frequency dependent skin and proximity effects.As discussed herein, a busbar assembly can include a single slot that isasymmetrically centered to allow one or more current sensing devices toaccess and measure differential fields. Based on the configuration ofthe single slot, the one or more current sensing devices are alsogalvanically isolated from a base of the busbar.

The positioning of the single slot within the busbar assembly can allowfor sensing of magnetic fields that have minimal frequency dependency.In other words, the position of the slot can provide a spatial positionwithin the busbar assembly that is appropriate for sensing a magneticfield and/or current ranging from current having direct current (DC)characteristics to current having a frequency characteristic up to ten(10) megahertz (MHz).

FIG. 1 depicts a schematic of an example of a plug-in hybrid-electricvehicle (PHEV). A vehicle 12 may include one or more electric machines14 mechanically connected to a hybrid transmission 16. The electricmachines 14 may be capable of operating as a motor and/or a generator.In addition, the hybrid transmission 16 can be mechanically connected toan engine 18. The hybrid transmission 16 can also be mechanicallyconnected to a drive shaft 20 that is mechanically connected to thewheels 22. The electric machines 14 can provide propulsion anddeceleration capability when the engine 18 is turned on or off. Theelectric machines 14 may also function as generators and can providefuel economy benefits by recovering energy that would normally be lostas heat in the friction braking system.

A traction battery 24, e.g., a battery pack, stores and provides energythat can be used by the electric machines 14 or other vehicle 12components. The traction battery 24 typically provides a high voltage DCoutput from one or more battery cell arrays, sometimes referred to asbattery cell stacks, within the traction battery 24. The high voltage DCoutput may also be converted to a low voltage DC output for applicationssuch as vehicle stop/start. The battery cell arrays may include one ormore battery cells. The traction battery 24 may be electricallyconnected to one or more power electronics modules 26 through one ormore contactors. The one or more contactors isolate the traction battery24 from other components when opened and connect the traction battery 24to other components when closed. The power electronics module 26 is alsoelectrically connected to the electric machines 14 and provides theability to bi-directionally transfer electrical energy between thetraction battery 24 and the electric machines 14. For example, a typicaltraction battery 24 may provide a DC voltage while the electric machines14 may require a three-phase AC voltage to function. The powerelectronics module 26 may convert the DC voltage to a three-phase ACvoltage as required by the electric machines 14. In a regenerative mode,the power electronics module 26 may convert the three-phase AC voltagefrom the electric machines 14 acting as generators to the DC voltagerequired by the traction battery 24. The description herein may beapplicable to a pure electric vehicle or other hybrid vehicles. For apure electric vehicle, the hybrid transmission 16 may be a gear boxconnected to an electric machine 14 and the engine 18 may not bepresent.

In addition to providing energy for propulsion, the traction battery 24may provide energy for other vehicle electrical systems. A typicalvehicle electrical system may include a DC/DC converter module 28 thatconverts the high voltage DC output of the traction battery 24 to a lowvoltage DC supply that is compatible with other vehicle loads. Otherhigh-voltage loads, such as compressors and electric heaters, may beconnected directly to the high-voltage without the use of a DC/DCconverter module 28. In a typical vehicle, the low-voltage systems areelectrically connected to an auxiliary battery 30, e.g., 12V battery.

A battery electrical control module (BECM) 33 may be in communicationwith the traction battery 24. The BECM 33 may function as a controllerfor the traction battery 24 and may also include an electronicmonitoring system that manages temperature and charge state of each ofthe battery cells. The traction battery 24 may have a temperature sensor31, such as a thermistor or other temperature gauge. The temperaturesensor 31 may be in communication with the BECM 33 to providetemperature data regarding the traction battery 24. The temperaturesensor 31 may also be located on or near the battery cells within thetraction battery 24. It is also contemplated that more than onetemperature sensor 31 may be used to monitor temperature of the batterycells.

The vehicle 12 may be, for example, an electric vehicle such as a PHEV,a FHEV, a MHEV, or a BEV in which the traction battery 24 may berecharged by an external power source 36. The external power source 36may be a connection to an electrical outlet. The external power source36 may be electrically connected to electric vehicle supply equipment(EVSE) 38. The EVSE 38 may provide circuitry and controls to regulateand manage the transfer of electrical energy between the power source 36and the vehicle 12. The external power source 36 may provide DC or ACelectric power to the EVSE 38. The EVSE 38 may have a charge connector40 for plugging into a charge port 34 of the vehicle 12. The charge port34 may be any type of port configured to transfer power from the EVSE 38to the vehicle 12. The charge port 34 may be electrically connected to acharger or on-board power conversion module 32. The power conversionmodule 32 may condition the power supplied from the EVSE 38 to providethe proper voltage and current levels to the traction battery 24. Thepower conversion module 32 may interface with the EVSE 38 to coordinatethe delivery of power to the vehicle 12. The EVSE connector 40 may havepins that mate with corresponding recesses of the charge port 34.

The various components discussed may have one or more associatedcontrollers to control and monitor the operation of the components. Thecontrollers may communicate via a serial bus (e.g., Controller AreaNetwork (CAN)) or via discrete conductors.

The battery cells, such as a prismatic cell, may include electrochemicalcells that convert stored chemical energy to electrical energy.Prismatic cells may include a housing, a positive electrode (cathode)and a negative electrode (anode). An electrolyte may allow ions to movebetween the anode and cathode during discharge, and then return duringrecharge. Terminals may allow current to flow out of the cell for use bythe vehicle. When positioned in an array with multiple battery cells,the terminals of each battery cell may be aligned with opposingterminals (positive and negative) adjacent to one another and a busbarmay assist in facilitating a series connection between the multiplebattery cells. The battery cells may also be arranged in parallel suchthat similar terminals (positive and positive or negative and negative)are adjacent to one another. For example, two battery cells may bearranged with positive terminals adjacent to one another, and the nexttwo cells may be arranged with negative terminals adjacent to oneanother. In this example, the busbar may contact terminals of all fourcells. The traction battery 24 may be heated and/or cooled using aliquid thermal management system, an air thermal management system, orother method as known in the art.

FIGS. 2A and 2B illustrate an example busbar assembly 100 according toan example implementation of the present disclosure. The busbar assembly100 includes a base 102 and a single asymmetrically positioned slot 104defined within the base 102, i.e., an aperture defined within the base102. In various implementations, the busbar assembly 100 can spanbetween a first battery cell and a second battery cell within thetraction battery 24. The busbar assembly 100 may also be located betweena battery, e.g., the traction battery 24, and other power electronicswithin the vehicle 12 and/or between a power electronics module and oneor more electric machines 14. The busbar assembly 100 may bemanufactured using a suitable metallic material to allow current flow.For example, the busbar assembly 100 may be comprised of copper, brass,and/or aluminum. The metallic material may include a first and a secondgenerally planar surface. Referring to FIG. 2B, the busbar assembly 100can define a channel 106 in some implementations as described in greaterdetail below.

Referring to FIG. 3, the base 102 of the busbar assembly 100 has athickness (T), a width (W), and a length (L). The slot 104 can beasymmetrically centered within the base 102 between a range ofapproximately 75% and approximately 79% of the width as measured from adistal side 108 of the base 102, which is referred to as a distance D,i.e., a center point of the slot is positioned between approximately 75%and approximately 79% of the width as measured from the distal side 108.In an example implementation, the slot 104 can be centered within thebase 102 such that the slot 104 is centered between approximately 76%and approximately 78% of the width as measured from the distal side 108.In another example implementation, the slot 104 can be centered withinthe base 102 at 77% of the width as measured from the distal side 108.In this context, the term “approximately” is known to those skilled inthe art. Alternatively, the term “approximately” may be read to meanplus or minus 5%.

In some implementations, the width of the slot 104 may range betweenabout two (2) millimeters (mm) and about four (4) millimeters (mm). Inan example implementation, the width of the slot 104 may be three (3)millimeters (mm). The width of the base 102 may range between aboutfifteen (15) millimeters (mm) and about fifty (50) millimeters (mm). Thethickness of the busbar assembly 100 can be a function of the width ofthe busbar assembly 100. In an example implementation, the width of thebusbar assembly 100 is at least four (4) times the thickness of thebusbar assembly 100 as defined in Equation 1:

W>4*T   Eqn. 1

Referring to FIG. 4, a printed circuit board 150 may be positioned overa generally planar surface 152 of the busbar assembly 100. A size of theprinted circuit board 150 may vary based on the electronic modulesand/or specialized sensing devices built in. The printed circuit board150 can be attached, i.e., mounted, to the busbar assembly 100 via anysuitable attachment techniques. For example, the printed circuit board150 may be mounted to the busbar assembly 100 via one or more fasteners,e.g., screws, bolts, etc. A frame (not shown) to retain the printedcircuit board 150 may also be attached to the busbar assembly 100. Theprinted circuit board 150 can include one or more electronic modules,e.g., components. As shown, the printed circuit board 150 can includeone or more current sensing devices 154. The printed circuit board 150can define a flanged portion 156 that extends outwardly away from theprinted circuit board 150 and has a width that is less than a width ofthe printed circuit board 150.

As shown in FIGS. 3 and 4, the one or more current sensing devices 154can be attached to the flanged portion 156. The flanged portion 156 maybe integral with the printed circuit board 150 in some implementations.In other implementations, the flanged portion 156 is separate and can beattached to the printed circuit board 150 via one or more connectors.The width of the flanged portion 156 is less than a width of the slot104 such that the flanged portion 156 and the one or more currentsensing devices 154 can extend through the slot 104 when the printedcircuit board 150 is attached to the busbar assembly 100.

The one or more current sensing devices 154 can comprise point fielddetectors (PFDs). The point field detectors can be used forhigh-bandwidth galvanically-isolated current sensing. The currentsensing device 154 can measure current parameters, e.g., differentialfield parameters, corresponding to current flow through the busbarassembly 100. As shown in FIG. 4, the current sensing device 154 and theflanged portion 156 extend into the channel 106. Depending on aconfiguration of the busbar assembly 100, a thickness of the channel 106can range between one (1) millimeter (mm) and two and a half (2.5)millimeters (mm). In these implementations, the current sensingdevice(s) 154 may extend beyond a generally planar surface 158 of thebusbar assembly 100. The busbar assembly 100 can include the channel 106when the thickness of the busbar assembly 100 is greater than apredetermined thickness.

While FIGS. 3 and 4 illustrate a single current sensing device 154, itis understood that two or more current sensing devices 154 can beattached to the printed circuit board 150. For example, a first currentsensing device may be attached to the flanged portion 156 such that thefirst current sensing device is proximal to the surface 152, and asecond current sensing device may be attached to the flanged portion 156such that the second current sensing device extends beyond a surface 160of the channel 106 and/or extends beyond the surface 158 when the base102 does not defined a channel 106. It is understood that the busbarassembly 100 may be manufactured such that a cross-section of the busbarsupports a range of current flow, e.g., ranging from about one hundred(100) Amperes (A) to about two thousand (2,000) Amperes.

Various components of the printed circuit board 150 may be connected toone or more controllers of the vehicle 12 such that the one or morecontrollers can receive the measurements from the one or more currentsensing devices 154. The current sensing devices 154 may be used tosense DC current provided by the traction battery 24 and/or phasecurrent for an inverter that is provided to the electric machines 14,e.g., motor and/or generator. While FIGS. 4 and 5 illustrate thenon-flanged portion of the printed circuit board 150 as being generallyperpendicular to the surface 152, in some example implementations, thenon-flanged portion of the printed circuit board 150 may be generallyparallel to the surface 152.

The description of the present disclosure is merely exemplary in natureand variations that do not depart from the gist of the presentdisclosure are intended to be within the scope of the presentdisclosure. Such variations are not to be regarded as a departure fromthe spirit and scope of the present disclosure.

What is claimed is:
 1. A busbar assembly, comprising: a base having awidth and a length, the base having a first surface and a secondsurface, the base having a first side and a second side, wherein adistance between the first side and the second side comprises the width,and wherein the base defines a slot centered between approximately 75%and approximately 79% of the width.
 2. The busbar assembly of claim 1,wherein the base defines the slot centered between approximately 76% andapproximately 78% of the width.
 3. The busbar assembly of claim 1,wherein the base defines the slot centered at 77% of the width.
 4. Thebusbar assembly of claim 1, wherein the slot comprises an apertureextending through the base.
 5. The busbar assembly of claim 1, whereinthe base further defines a channel between the first side and the secondside.
 6. The busbar assembly of claim 5, further comprising a printedcircuit board disposed over the first surface, wherein a flanged portionof the printed circuit board extends through the channel, the flangedportion including at least one current sensing device configured tomeasure current parameters of current flow through the base.
 7. Thebusbar assembly of claim 6, wherein the at least one current sensingdevice comprises a point field detector.
 8. The busbar assembly of claim6, wherein the at least one current sensing device is galvanicallyisolated from the base.
 9. The busbar assembly of claim 1, wherein thewidth is at least four times a thickness of the base.
 10. A busbarassembly, comprising: a base having a width and a length, the basehaving a first surface and a second surface, the base having a firstside and a second side, wherein a distance between the first side andthe second side comprises the width, wherein the base defines a slotcentered between approximately 75% and approximately 79% of the width;and a printed circuit board disposed over the first surface, wherein aflanged portion of the printed circuit board extends through a channel,the flanged portion including at least one current sensing deviceconfigured to measure current parameters of current flow through thebase.
 11. The busbar assembly of claim 10, wherein the base defines theslot centered between approximately 76% and approximately 78% of thewidth.
 12. The busbar assembly of claim 10, wherein the base defines theslot centered at 77% of the width.
 13. The busbar assembly of claim 10,wherein the slot comprises an aperture extending through the base. 14.The busbar assembly of claim 10, wherein the base further defines thechannel between the first side and the second side.
 15. The busbarassembly of claim 10, wherein the at least one current sensing devicecomprises a point field detector.
 16. The busbar assembly of claim 10,wherein the at least one current sensing device is galvanically isolatedfrom the base.
 17. The busbar assembly of claim 10, wherein the width isat least four times a thickness of the base.
 18. A busbar assembly,comprising: a base having a width and a length, the base having a firstsurface and a second surface, the base having a first side and a secondside, wherein a distance between the first side and the second sidecomprises the width, wherein the base defines a slot centered betweenapproximately 75% and approximately 79% of the width and the width is atleast four times a thickness of the base; and a printed circuit boarddisposed over the first surface, wherein a flanged portion of theprinted circuit board extends through a channel, the flanged portionincluding at least one current sensing device configured to measurecurrent parameters of current flow through the base.
 19. The busbarassembly of claim 18, wherein the base defines the slot centered betweenapproximately 76% and approximately 78% of the width.
 20. The busbarassembly of claim 18, wherein the base defines the slot centered at 77%of the width.